Ventilator

ABSTRACT

A main body casing of a ventilator is formed with an outer airflow opening and an inner airflow opening and a ventilating path for connecting these airflow openings is formed in the main body casing. The ventilator ventilates a room and prevents entry of noise from outside into the room through the ventilating path. The ventilating path is bifurcated and these two ventilating paths have different lengths from each other so that a noise sound wave entering through one of the ventilating paths and a noise sound wave entering through the other ventilating path are out of phase with each other to cancel out each other&#39;s sound wave energy when the sound waves meet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a ventilator having a sound-deadening function for reducing noise from outside while maintaining ventilation performance.

2. Description of the Related Art

As examples of prior art for preventing entry of unnecessary sound while carrying out ventilation of a building, there are Japanese Patent Application Laid-open (JP-A) No. 62-29691 and JP-A No. 57-122234. In JP-A No. 62-29691, a ventilating opening is provided to a door frame and a plurality of shielding plates are provided in the ventilating opening to form a meandering ventilation passage to thereby prevent sounds in the room from escaping into an adjacent room through the ventilating opening. In JP-A No. 57-122234, a ventilating opening is provided to a wall and a position of a hole of the ventilating opening formed in one room and a position of a hole of the ventilating opening formed in the other room are displaced from each other in a vertical direction so that they do not overlap each other to thereby prevent sound from escaping into the adjacent room.

In the techniques shown in the above Japanese Patent Documents, sound-absorbing material is stuck on an inner wall of the meandering ventilation passage and a noise sound wave is absorbed by the sound-absorbing material while traveling through the ventilation passage to thereby reduce noise energy. Therefore, a long ventilation passage is required to obtain high sound-deadening effect, which results in increase in dimensions of a sound-deadening mechanism portion. If the sound-deadening mechanism portion is formed to meander in a thickness direction of the door or wall so as to secure a length of the ventilation passage, a protruding dimension from the door or wall increases. If the sound-deadening mechanism portion is formed to meander in a height direction of the door or wall, a proportion of the sound-deadening mechanism portion to a surface area of the door or wall increases. Moreover, the longer the ventilation passage or the more the ventilation passage meanders, the larger resistance to the ventilation becomes and the lower ventilation efficiency becomes.

SUMMARY OF THE INVENTION

The present invention has been made to cope with the problems of the above prior art and it is an object of the invention to provide a ventilator mounted to a wall of a building to ventilate the building, the ventilator having satisfactory ventilation performance and having sound insulation performance at the same time without requiring a long ventilation passage.

According to the invention, there is provided a ventilator which comprises a main body casing having an outer wall and an inner wall, in which a ventilating path for connecting an airflow opening formed in the outer wall and an airflow opening formed in the inner wall is provided in the main body casing, and the ventilator ventilates a room on which the ventilator is attached through the inner wall thereof and prevents entry of noise from outside into the room through the ventilating path. The ventilating path is bifurcated into two, and the bifurcated two ventilating paths each extending to a confluence of the ventilating paths have different lengths from each other so that a noise sound wave passing through one of the ventilating paths and a noise sound wave passing through the other ventilating path are out of phase with each other to cancel out each other's energy when the sound waves meet at the confluence.

A box-shaped sound-deadening chamber stuffed with sound-deadening material may be disposed at a central portion in the main body casing to receive the sound wave reflected by outer faces of partition walls forming the ventilating paths.

A part of the one ventilating path and a part of the other ventilating path may be respectively formed of punched panels, and sound-deadening chambers stuffed with sound-deadening material may be formed outside the punched panels and between the punched panels and the wall forming the main body casing.

A sound wave reflecting plate is provided in a position in the main body casing which faces the airflow opening formed in the outer side wall to reflect the sound waves entering the main body casing through the airflow opening toward the airflow opening, thereby introducing the sound waves which have not been discharged outside the main body casing through the airflow opening into the bifurcated two ventilating paths.

In the invention, air circulation into and out of the room through the ventilating paths is carried out and especially outside air is introduced into the room. At this time, the noise sound waves from outside noise sources enter through the ventilating paths. The ventilating paths branch off the outer airflow opening, join at the inner airflow opening, and have different lengths from each other. Therefore, when the noise sound wave entering through one of the ventilating paths and the noise sound wave entering through the other ventilating path meet, phases inverted with respect to each other meet to cancel out and attenuate each other's sound wave energy. Moreover, the sound-deadening chambers are formed in the device main body (main body casing) and the reflecting plate is formed on the wall faces of the ventilating paths. Therefore, the noise sound waves entering through the ventilating paths are introduced into the sound-deadening chambers and sound pressure energy is attenuated. As a result, it is possible to provide the ventilator having both the sound-deadening effect and ventilating performance without having a long ventilating path on which sound-absorbing material is stuck.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of the embodiment with reference to the accompanying drawings wherein:

FIG. 1 is a drawing showing a state in which an embodiment of a ventilator according to the invention is installed on one side of a window frame;

FIG. 2 is a sectional view showing an inner structure of the ventilator shown in FIG. 1;

FIG. 3 is a drawing for explaining ventilating operation in the ventilator shown in FIG. 2; and

FIG. 4 is a drawing for explaining sound-deadening operation in the ventilator shown in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A structure of an embodiment of a ventilator according to the present invention will be described by using FIGS. 1 and 2.

As shown in FIG. 2, the ventilator 1 is mainly provided in a longitudinal direction of a window frame 2 and air flows into and out of a room to some extent through the ventilator 1 even when a window 3 is closed.

A main body casing 4 of the ventilator 1 is formed in a box shape surrounded with an outer wall 4 a, an inner wall 4 b, and left and right side walls 4 c, 4 d as shown in FIG. 2. At a central portion in a width direction of the outer wall 4 a, an outer airflow opening 5 is open. In a position displaced from a central portion in a width direction of the inner wall 4 b toward one side wall 4 d (right side wall in FIG. 2), an inner airflow opening 6 is open. The outer airflow opening 5 mainly functions as an outside air intake for introducing outside air into a room and is attached with a filter body 7 for preventing entry of dirt, dust, and the like from outside. The inner airflow opening 6 mainly functions as an outside air inlet for sending the outside air taken in through the outer airflow opening 5 into the room and is opened and closed with an opening/closing flap 8 to respond to need or no need of ventilation.

The outer airflow opening 5 and the inner airflow opening 6 communicate with each other through two independent ventilating paths 9, 10 formed in the main body casing 4. These two ventilating paths 9, 10 branch off from a vicinity of the outer airflow opening 5 and join in a vicinity of the inner airflow opening 6.

In a central position in the main body casing 4, a central sound-deadening chamber 11 stuffed with sound-absorbing material 12 is provided. The central sound-deadening chamber 11 is a box-shaped structure open toward the outer airflow opening 5 and disposed in a position surrounded with the two ventilating paths 9, 10 and has a role in taking in noise in the ventilating paths 9, 10 to attenuate sound pressure energy.

Moreover, structures of the ventilating paths 9, 10 and the central sound-deadening chamber 11 will be described with reference to FIG. 2.

The first ventilating path 9 is defined with an outer partition wall 13 and an inner partition wall 14 in the main body casing 4 and has a shape curved toward the center of the main body casing 4. The outer partition wall 13 forming the ventilating path 9 is formed of an arc wall portion 13 b extending from a vicinity of an opening edge of the outer airflow opening 5 to the left side wall 4 c of the main body casing 4 and an elliptic wall portion 13 c extending from the left side wall 4 c of the main body casing 4 to the center of the main body casing 4. One end of the arc wall portion 13 b is a distal end 13 a of the ventilating path 9 and one end of the elliptic wall portion 13 c is an end 13 d of the ventilating path 9.

The arc wall portion 13 b is formed by forming a punched panel into an arc shape. The elliptic wall portion 13 c is formed by forming a flat panel into an ellipse. A space formed between a back face of the arc wall portion 13 b and a corner of the main body casing 4 is formed into a corner sound-deadening chamber 20 stuffed with sound-absorbing material 19.

The inner partition wall 14 forming the first ventilating path 9 is formed of an elliptic wall 14 b. One end (a distal end 14 a of the inner partition wall 14) of the elliptic wall 14 b is positioned at a position of a first focus f1 of the elliptic wall portion 13 c forming the outer partition wall 13 and the other end (an end 14 c of the inner partition wall 14) enters the central sound-deadening chamber 11 and extends to a center line CL passing through the outer airflow opening 5. Furthermore, the outer partition wall 13 and the inner partition wall 14, which forms the first ventilating path 9, are disposed to have a positional relationship such that a second focus f2 of the elliptic wall portion 13 c of the outer partition wall 13 and a first focus f3 of the elliptic wall 14 b of the inner partition wall 14 coincide with each other.

The second ventilating path 10 is defined with an outer partition wall 15 and an inner partition wall 16 and disposed so that the first ventilating path 9 and the second ventilating path 10 are symmetric with respect to the center line CL in the main body casing 4. Therefore, description of this structure will be omitted.

The central sound-deadening chamber 11 is in the box shape open toward the outer airflow opening 5 and receives, from its opening 11 a into itself, one end of the inner partition wall 14 forming the first ventilating path 9 and one end of the inner partition wall 16 forming the second ventilating path 10. The elliptic wall 14 b of the inner partition wall 14 forming the first ventilating path 9 is disposed so that its second focus f4 coincides with a position of the opening 11 a of the central sound-deadening chamber 11. Moreover, the central sound-deadening chamber 11 is not in close contact with the inner wall 4 b of the main body casing 4 but disposed while spaced from the inner wall 4 b. Therefore, an extension ventilating path 17 extending from the first ventilating path 9 to the inner airflow opening 6 is formed between the inner wall 4 b and (a bottom portion of) the central sound-deadening chamber 11.

A sound wave reflecting plate 18 having a parabolic section is disposed in the main body casing 4 to face the outer airflow opening 5 so that a focus f5 of a parabola of the section coincides with a position of the outer airflow opening 5.

The outer airflow opening 5 is an entrance shared between the first ventilating path 9 and the second ventilating path 10 and formed on the center line CL of the main body casing 4. On the other hand, the inner airflow opening 6 is an exit shared between the first ventilating path 9 and the second ventilating path 10 and formed in a position displaced from the center line CL of the main body casing 4 toward one (right) side wall 4 d. As a result, a length of the first ventilating path 9 and a length of the second ventilating path 10 are not equal to each other and the first ventilating path 9 is longer than the second ventilating path 10 by a length of the extension ventilating path 17 formed between the inner wall 4 b and the bottom portion of the central sound-deadening chamber 11.

A difference between the lengths of the first ventilating path 9 and the second ventilating path 10 brings about a sound-deadening function for minimizing the noise passing through the main body casing 4 and entering the room after the noise has been taken in through the outer airflow opening 5. In other words, when sound waves which have not been silenced by the central sound-deadening chamber 11, out of the noise taken into the main body casing 4 from the outer airflow opening 5, pass through the first ventilating path 9 and the second ventilating path 10 and join, the sound wave having a certain phase and the sound wave having an inverted phase overlap each other and cancel out each other's sound pressure energy to exert the sound-deadening effect since the lengths of the first ventilating path 9 and the second ventilating path 10 are different. For this purpose, the extension ventilating path 17 is designed to have a length such that the sound wave from the first ventilating path 9 has an inverted phase with respect to a phase of the sound wave from the second ventilating path 10.

Next, ventilating operation and sound-deadening operation of the ventilator 1 shown in FIG. 2 will be described with reference to FIGS. 3 and 4.

First, the ventilating operation of the ventilator 1 will be described. When the opening/closing flap 8 is opened, outside air is taken into the main body casing 4 through the outer airflow opening 5. The outer airflow opening 5 is attached with a filter body 7 and entry of dirt and dust is suppressed. The taken-in outside air is introduced while divided into the curved first ventilating path 9 and second ventilating path 10, as a result, a volume of air that flows in can be suppressed and entry of rain or the like can be also suppressed. The outside air that has passed through the first ventilating path 9 and the outside air that has passed through the second ventilating path 10 finally join each other and are introduced into the room through the inner airflow opening 6. Because opening and closing of the opening/closing flap 8 only provide a choice between ventilation and interruption of ventilation, it is preferable to provide slits for manually adjusting an opening degree of the inner airflow opening 6 in a vicinity of the airflow opening 6 or an air volume regulating valve or the like of which an opening degree changes automatically according to the air volume.

Next, the sound-deadening operation of the ventilator 1 will be described. If the opening/closing flap 8 is opened, noise sound waves are taken into the main body casing 4 through the outer airflow opening 5. The noise sound waves that have entered from the outer airflow opening 5 are first reflected by the sound wave reflecting plate 18 toward the focus f5 coincident with the outer airflow opening 5 and a part of the sound waves are caused to rebound outward through the outer airflow opening 5 again (the first sound deadening).

The sound waves not reflected by the sound wave reflecting plate 18 are introduced into the first ventilating path 9 and the second ventilating path 10 and advance to the elliptic wall portion 13 c of the outer partition wall 13 and the elliptic wall portion of the outer partition wall 15 while reflected diffusely between the outer partition wall 13 and the inner partition wall 14, which forms the first ventilating path 9, and between the outer partition wall 15 and the inner partition wall 16, which form the second ventilating path 10. During this advancement, the noise sound waves are taken through the arc wall portion 13 b formed of the punched panel into the corner sound-deadening chamber 20 behind the arc wall portion 13 b and diffusely reflected over and over in the corner sound-deadening chamber 20. In this way, the reflected waves cancel out each other's energy and energy of the sound waves is reduced by the action of the sound-absorbing material 19. As a result, the energy of the noise sound waves is substantially reduced and deadened. Moreover, the sound pressure is attenuated by the action of energy losses of the reflected waves due to the diffused reflection between the outer partition wall 13 and the inner partition wall 14 (the second sound deadening).

The sound waves which have reached the elliptic wall portion 13 c of the outer partition wall 13 are reflected by the elliptic wall portion 13 c. At this time, because the distal end 14 a of the inner partition wall 14 coincides with the first focus f1 of the elliptic wall portion 13 c of the outer partition wall 13, the sound waves advancing through an opening d1 (see FIG. 4) formed between the distal end 14 a of the inner partition wall 14 and an end of the arc wall portion 13 b of the outer partition wall 13 (a joint with the elliptic wall portion 13 c) collide with the elliptic wall portion 13 c from positions outside the first focus f1 of the elliptic wall portion 13 c. Therefore, the sound waves reflected by the elliptic wall portion 13 c advance toward positions outside the second focus f2 of the elliptic wall portion 13 c. Because an end 13 d of the outer partition wall 13 is bent toward the second focus f2 of the elliptic wall portion 13 c, the sound waves reflected by the elliptic wall portion 13 c concentrate onto a bay-shaped space d2 formed of the end 13 d and the elliptic wall portion 13 c of the outer partition wall 13 and become less liable to jump out into the ventilating path. As a result, entry of the sound waves into the room is reduced (the third sound deadening).

The sound waves which have jumped out of the elliptic wall portion 13 c of the outer partition wall 13 are reflected by the elliptic wall 14 b of the inner partition wall 14. Here, because the first focus f3 of the elliptic wall 14 b coincides with the second focus f2 of the elliptic wall portion 13 c of the outer partition wall 13, the sound waves which have jumped out of an opening d3 formed between the distal end 14 a of the inner partition wall 14 and the end 13 d of the outer partition wall 13 collide with the elliptic wall 14 b from outside the first focus f3 of the elliptic wall 14 b of the inner partition wall 14. Therefore, the sound waves reflected by the elliptic wall 14 b are introduced into the central sound-deadening chamber 11 through an opening d4 of the central sound-deadening chamber 11. The noise sound waves which have entered the central sound-deadening chamber 11 are diffusely reflected over and over in the central sound-deadening chamber 11. In this way, the reflected waves cancel out each other's energy and energy of the sound waves is reduced by the action of the sound-absorbing material 12 provided in the central sound-deadening chamber 11. As a result, the energy of the noise sound waves is substantially reduced and deadened (the fourth sound deadening).

The sound waves which have been reflected by the elliptic wall 14 b of the inner partition wall 14 and have not been taken into the central sound-deadening chamber 11 and the sound waves which have returned into the ventilating path from the central sound-deadening chamber 11 are finally advance toward the inner airflow opening 6 from an opening d5 formed between an opening edge of the central sound-deadening chamber 11 and a bend of the elliptic wall portion 13 c of the outer partition wall 13. When the sound waves having phases inverted with respect to each other meet at a confluence P of the first ventilating path 9 and the second ventilating path 10, the sound pressure energy is attenuated (the fifth sound deadening).

The noise sound waves taken into the main body casing 4 through the outer airflow opening 5 are subjected to the step-by-step sound deadening in the main body casing 4 and therefore entry of the sound waves into the room can be minimized. Although it is difficult to deaden all of the noise sound waves coming in through the outer airflow opening 5 and the noise sound waves which have not been deadened escape into the room through the inner airflow opening 6, the sound pressure energy of the sound waves is substantially reduced and sufficient sound-deadening effect can be obtained.

Although the partition walls of the ventilator of the above-described embodiment form the perfect arc wall and the perfect elliptic walls, it is possible to bend a panel into a polygonal shape or successively connect panels to form an approximate arc and an approximate ellipse. In this case, though the directions of the reflection become irregular, sufficient sound-deadening performance can be obtained due to the sound deadening in a plurality of steps described above. 

1. A ventilator which comprises a main body casing having an outer wall and an inner wall, in which a ventilating path for connecting an airflow opening formed in the outer wall and an airflow opening formed in the inner wall is provided in the main body casing, and the ventilator ventilates a room on which the ventilator is attached through the inner wall thereof and prevents entry of noise from outside into the room through the ventilating path, wherein the ventilating path is bifurcated into two, and the bifurcated two ventilating paths each extending to a confluence of the ventilating paths have different lengths from each other so that a noise sound wave passing through one of the ventilating paths and a noise sound wave passing through the other ventilating path are out of phase with each other to cancel out each other's energy when the sound waves meet at the confluence.
 2. The ventilator according to claim 1, wherein a box-shaped sound-deadening chamber stuffed with sound-deadening material is disposed at a central portion in the main body casing to receive the sound wave reflected by outer faces of partition walls forming the ventilating paths.
 3. The ventilator according to claim 1, wherein a part of the one ventilating path and a part of the other ventilating path are respectively formed of punched panels, and sound-deadening chambers stuffed with sound-deadening material are formed outside the punched panels and between the punched panels and the wall forming the main body casing.
 4. The ventilator according to claim 1, wherein a sound wave reflecting plate is provided in a position in the main body casing which faces the airflow opening formed in the outer side wall to reflect the sound waves entering the main body casing through the airflow opening toward the airflow opening, thereby introducing the sound waves which have not been discharged outside the main body casing through the airflow opening into the bifurcated two ventilating paths. 